Hydraulic cylinders are commonly utilized in underwater, muddy or other fully or partially submerged environments. Such mechanisms are featured, for example, on marine pumps, submerged lifts and particularly boat lifts. In such situations, the cylinder mechanism is apt to become fouled or contaminated due to dirt, debris, marine growth, minerals and other contaminants collecting on the cylinder rod. Over time, this debris can be gradually pulled into the cylinder, which can eventually interfere with operation of the mechanism. As a result, such cylinders typically require periodic cleaning, repair and/or replacement. This can be time consuming and expensive and is likely to interrupt use of the hydraulic cylinder mechanism.
Conventionally, a collapsible boot or bellows element has provided the most common form of protection for a submerged hydraulic cylinder rod. Unfortunately, in underwater environments, such boots do not operate in an optimally effective manner. Unless the submerged boot is vented, it will tend to implode as the cylinder rod extends due to the density of the water and its resistance to being sucked into the expanding boot. Conversely, when the cylinder rod retracts and the boot collapses, water previously trapped within the boot causes the boot to balloon. Such constant and repeated imploding and ballooning of the boot can cause the boot to prematurely deteriorate and eventually fail. The protective bellows elements have thus been vented to facilitate drawing the water into the boot. However, this tends to introduce a considerable amount of contaminants into the bellows element, which eventually collect on and interfere with operation of the cylinder rod.
In an attempt to overcome the foregoing problems, U.S. Pat. No. 8,291,810 has added a flapper valve across the boot vent. The valve opens to suck water into the boot as the boot expands and subsequently opens to exhaust water from the boot when the cylinder rod retracts and the boot collapses. This permits water to flow into and out of the bellows element as the cylinder operates. The flapper valve therefore reduces the previously described problem of the alternating imploding and ballooning of the boot somewhat. However, water and accompanying minerals, dirt and debris continue to collect on and contaminate the hydraulic cylinder, which can damage the submerged cylinder over extended periods of time. In order to reduce the contaminants that inevitably foul the cylinder rod, U.S. Pat. No. 8,291,810 also employs a series of scrubbers, which complicate the construction and increase the expense of the protective bellows element considerably.